The predominant interest of our laboratory is to study the innate immune system in vertebrates and insects. Our focus is to define the structure and function of pattern recognition molecules that appear to selectively recognize the patterns of oligosaccharides that decorate microorganisms from self-glycoproteins. The mannose-binding lectin (MBL) is one such molecule which functions like an ante-antibody and is regarded as a prototypic mammalian pattern recognition molecule. MBL appears to play a role in first line host defense in the lag period that is required to generate a long lasting adaptive immune response. A hallmark of innate immunity is that it is now recognized as a necessary antecedent for the development of an adaptive immune response. Little or no attention has been paid as to whether MBL is able to interact and prime the development of adaptive immunity, in particular systemic lupus erythematosis (SLE), we believe that MBL plays a role B cell homeostasis. The goal of this proposal is to explore this question by making use of unique MBL null mou7se models that we have generated in our laboratory in conjunction with other known lupus prone animal models.